1. Field of the Invention
This invention relates to a re-radiating antenna system and more specifically to technology improving a wearable antenna.
2. Description of the Related Art
When carrying a portable wireless device such as a cellular telephone, a cordless telephone or a small transceiver or the like, the device itself is usually inserted inside a garment pocket or it may be placed in a special holder for the purpose which is attached to a belt for example. This brings the antenna of the portable wireless device into close proximity with the body of the carrier however, which leads to the problem of the effect of electromagnetic waves emitted from the portable wireless device on the body of the person carrying the device as well as a problem of a change in the impedance of the antenna which inhibits the antenna effectively radiating radio waves. Further, some of the radio waves emitted from the antenna are absorbed by the body of the carrier leading to the problem that these absorbed radio waves are not used effectively for communication, while there is also a problem of incoming radio waves being prevented from being adequately received. Many different solutions have been investigated to provide means for avoiding the effect on the human body during a conversation using a portable telephone, however even when not being used for a conversation a portable telephone continues transmitting and receiving radio waves. Solutions to the problem of the effects on the human body of electromagnetic waves when a portable telephone is not being used and solutions to the adverse effects that the carrier exerts on an antenna have not been sufficiently investigated. The invention disclosed in Japanese Unexamined Patent Application No. 2002-135020 proposes a solution of a reflector plate attached to the device holder, however efficient transmission and reception of radio waves using this method requires adequate separation of the reflecting plate and the antenna of the portable wireless device which raises further issues of practicality.
To provide an effective antenna that can be carried while walking, research is being conducted on wearable patch antennas that allow an antenna to be housed in clothing or a hat for example (The Institute of Electronics, Information and Communication Engineers B-1-108, 2002). This antenna has various features such that the effect on the human body of electromagnetic waves radiation is small, it can be installed in a high position on the human body to alleviate effects on people and things near the antenna, and so on, however thus far the problem of the method of power supply for the antenna has not been adequately investigated. If for example a solid part like a connector or the like is used with a power supply means for an antenna it creates difficulties attaching the antenna to the body, detracting from the advantages offered by having a wearable antenna constructed of a flexible material. It also has other disadvantages such as the need to connect apparel in which the antenna is housed with a portable wireless device.
Further, when the portable wireless device is placed in a location such as a room for example where it is difficult for radio waves to reach, it is effective to have an externally connected antenna for installation outside for connection to the portable wireless device, however this requires a connector to connect the externally attached antenna to the portable wireless device but the act of disconnecting and reconnecting is inconvenient.